[show abstract][hide abstract] ABSTRACT: Conservation policies usually focus on in situ protection of native populations, a priority that requires accurate assessment of population status. Distinction between native and introduced status can be particularly difficult (and at the same time, is most important) for species whose natural habitat has become both rare and highly fragmented. Here, we address the status of the white elm (Ulmus laevis Pallas), a European riparian tree species whose populations have been fragmented by human activity and is protected wherever it is considered native. Small populations of this species are located in Iberia, where they are unprotected because they are considered introductions due to their rarity. However, Iberia and neighbouring regions in southwestern France have been shown to support discrete glacial refuge populations of many European trees, and the possibility remains that Iberian white elms are native relicts. We used chloroplast RFLPs and nuclear microsatellites to establish the relationship between populations in Iberia and the Central European core distribution. Bayesian approaches revealed significant spatial structure across populations. Those in Iberia and southwestern France shared alleles absent from Central Europe, and showed spatial population structure within Iberia common in recognized native taxa. Iberian populations show a demographic signature of ancient population bottlenecks, while those in Central European show a signature of recent population bottlenecks. These patterns are not consistent with historical introduction of white elm to Iberia, and instead strongly support native status, arguing for immediate implementation of conservation measures for white elm populations in Spain and contiguous areas of southern France.Heredity advance online publication, 11 September 2013; doi:10.1038/hdy.2013.81.
[show abstract][hide abstract] ABSTRACT: To understand the evolutionary consequences of hybridization between the outcrossing plant Geum rivale (Rosaceae) and the selfer Geum urbanum, we tested the predictions of two simple models that assume either (A) low or (B) high pollen fitness in hybrids. Model A predicts only four genotypic classes (G. rivale, G. rivale backcross [BCR ], F1, and Geum urbanum) and asymmetric introgression from inbreeding to outbreeding species. Model B predicts additional genotypic classes and potential generation of novel inbreeding lines in the hybrid swarm. Amplified fragment length polymorphism (AFLP) analysis of adults revealed only the four genotypes predicted by model A. However, microsatellite analysis of parent-progeny arrays demonstrated production of selfed offspring by F1 and BCR maternal parents and contribution of these genotypes to outcross pollen pools, as predicted by model B. Moreover, AFLP and morphological analysis showed that the offspring generation comprised genotypes and phenotypes covering the entire spectrum of variation between the two parental species, in line with model B. A common garden experiment indicated no systematic reduction in fitness of offspring derived from hybrid parents. The genetic structure of the adults in the Geum hybrid swarm cannot be explained by restricted mating patterns but may result from ecological selection acting on a diverse offspring population.
[show abstract][hide abstract] ABSTRACT: New Caledonia is a global biodiversity hotspot facing extreme environmental degradation. Given the urgent need for conservation prioritisation, we have made a first-pass quantitative assessment of the distribution of Narrow Endemic Species (NES) in the flora to identify species and sites that are potentially important for conservation action. We assessed the distributional status of all angiosperm and gymnosperm species using data from taxonomic descriptions and herbarium samples. We characterised species as being NES if they occurred in 3 or fewer locations. In total, 635 of the 2930 assessed species were classed as NES, of which only 150 have been subjected to the IUCN conservation assessment. As the distributional patterns of un-assessed species from one or two locations correspond well with assessed species which have been classified as Critically Endangered or Endangered respectively, we suggest that our distributional data can be used to prioritise species for IUCN assessment. We also used the distributional data to produce a map of "Hotspots of Plant Narrow Endemism" (HPNE). Combined, we used these data to evaluate the coincidence of NES with mining activities (a major source of threat on New Caledonia) and also areas of conservation protection. This is to identify species and locations in most urgent need of further conservation assessment and subsequent action. Finally, we grouped the NES based on the environments they occurred in and modelled the habitat distribution of these groups with a Maximum Entropy Species Distribution Model (MaxEnt). The NES were separable into three different groups based primarily on geological differences. The distribution of the habitat types for each group coincide partially with the HPNE described above and also indicates some areas which have high habitat suitability but few recorded NES. Some of these areas may represent under-sampled hotspots of narrow endemism and are priorities for further field work.
PLoS ONE 01/2013; 8(9):e73371. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: • Premise of the study: Microsatellite markers were developed for the hemiparasitic plant Melampyrum sylvaticum to investigate the breeding system, genetic diversity, and structure of populations in the United Kingdom, Sweden, and Norway.• Methods and Results: Microsatellites were isolated from genomic DNA using an enrichment protocol. Twenty-nine loci were characterized in two individuals from each of 15 geographically disparate populations ("global"). Seven polymorphic loci were further characterized in one population ("local"). The number of alleles per locus ranged from two to 12 in the global sample and one to seven in the local sample. The expected heterozygosity ranged from 0-0.75, the observed heterozygosity from 0-0.1, and the inbreeding coefficient from 0.84-1 in the local sample.• Conclusions: The results show the utility of these novel polymorphic microsatellite markers for further conservation genetic analyses. The strong deficit of heterozygosity across all loci in the local sample suggests the species may be inbreeding.
American Journal of Botany 10/2012; · 2.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: Rare and threatened subarctic willow scrub communities in the UK are the subject of ongoing conservation programmes, yet little is known about the diversity of fungal taxa that they support. Isolates of the rust genus Melampsora were sampled from 112 leaves of eight subarctic willow (Salix) taxa and their hybrids from twelve sites in the UK. In order to determine the number of Melampsora taxa present in the samples, isolates were sequenced for the Internal Transcribed Spacer (ITS) region of rDNA and data were subject to phylogenetic analysis. Maximum likelihood and Bayesian analysis indicated that the isolates fell into three strongly supported host-associated clades. Clade I contained only isolates from Salix herbacea and was distinguished morphologically by dense urediniospore echinulation and thin cell walls. Clade II contained isolates from Salix arbuscula and Salix reticulata only. These could not be distinguished morphologically from isolates in Clade III which were found on Salix lapponum, Salix myrsinites, Salix myrsinifolia, Salix aurita, Salix lanata, and their hybrids. Clade II was most distinct in ITS sequence, differing by 50 bases from Clades I and III, while the latter clades differed in sequence by only 24 bases on average. Clades I and III are likely to represent the previously recognised taxa Melampsora alpina Juel 1894 and Melampsora epitea Thüm. 1879 respectively, but Clade II has not apparently been described before. Significant differences in the intensity of infection by isolates of Clade III were found among different Salix species at a single site, suggesting either differences in resistance among Salix taxa, or the presence of further cryptic taxa within Clade III. The study illustrates the power of molecular phylogenetic analysis to reveal cryptic biodiversity within Melampsora, and suggests that conserving Salix host diversity within subarctic willow communities will ensure that a diversity of associated Melampsora taxa is maintained.
[show abstract][hide abstract] ABSTRACT: Six DNA regions were evaluated as potential DNA barcodes for Fungi, the second largest kingdom of eukaryotic life, by a multinational, multilaboratory consortium. The region of the mitochondrial cytochrome c oxidase subunit 1 used as the animal barcode was excluded as a potential marker, because it is difficult to amplify in fungi, often includes large introns, and can be insufficiently variable. Three subunits from the nuclear ribosomal RNA cistron were compared together with regions of three representative protein-coding genes (largest subunit of RNA polymerase II, second largest subunit of RNA polymerase II, and minichromosome maintenance protein). Although the protein-coding gene regions often had a higher percent of correct identification compared with ribosomal markers, low PCR amplification and sequencing success eliminated them as candidates for a universal fungal barcode. Among the regions of the ribosomal cistron, the internal transcribed spacer (ITS) region has the highest probability of successful identification for the broadest range of fungi, with the most clearly defined barcode gap between inter-and intraspecific variation. The nuclear ribosomal large subunit, a popular phylogenetic marker in certain groups, had superior species resolution in some taxonomic groups, such as the early diverging lineages and the ascomycete yeasts, but was otherwise slightly inferior to the ITS. The nuclear ribosomal small subunit has poor species-level resolution in fungi. ITS will be formally proposed for adoption as the primary fungal barcode marker to the Consortium for the Barcode of Life, with the possibility that supplementary barcodes may be developed for particular narrowly circumscribed taxonomic groups.
Proceedings of the National Academy of Sciences 04/2012; 109(16):6241-6246. · 9.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: Aims In situ species survival involves persistence at current sites and/or colonization of new locations. Determining the likelihood of these events requires an understanding of population dynamics and dispersal. We address these issues in populations of a critically endangered tropical conifer Araucaria nemorosa and provide conservation recommendations.Location Port Boise, island of Grand Terre, New Caledonia, Pacific Ocean.Methods We characterize the demographic structure of six populations of A. nemorosa based upon size class frequencies and relative basal area compared to competing angiosperm trees. Using genotype data from 280 adult individuals at seven microsatellite loci, we indirectly estimate dispersal distances and project a maximal dispersal envelope around the extant populations.Results Our survey detected marked differences in demographic parameters including the proportion of basal area occupied by A. nemorosa versus angiosperm trees (ranging from 25% to 77%), the size class frequency distributions of A. nemorosa and seedling densities (ranging from 500 to 37300 seedlings ha−1) among some populations. Wright’s genetic neighbourhood ranged from 22 to 876 trees, and historic gene dispersal ranged from 10.8 to 82.4 m, indicating that most seed dispersal is <100 m.Main conclusions This study indicates that the risk of recruitment failure in remnant populations of Araucaria nemorosa is low in most of the stands but is high in the inland population Forêt Nord. In situ natural regeneration appears to be constrained in this population, most likely as a consequence of competitive exclusion. Our results also suggest that the majority of seed dispersal is too short to allow A. nemorosa to disperse to new more hospitable sites within an ecologically relevant time-scale. Our findings have implications not only for this emblematic tree species but also for a wide range of fragmented and degraded plant species populations with limited dispersal that are vulnerable to competitive exclusion.
[show abstract][hide abstract] ABSTRACT: DNA barcoding in the land plants presents a number of challenges compared to DNA barcoding in many animal clades. The CO1 animal DNA barcode is not effective for plants. Plant species hybridize frequently, and there are many cases of recent speciation via mechanisms, such as polyploidy and breeding system transitions. Additionally, there are many life-history trait combinations, which combine to reduce the likelihood of a small number of markers effectively tracking plant species boundaries. Recent results, however, from the two chosen core plant DNA barcode regions rbcL and matK plus two supplementary regions trnH-psbA and internal transcribed spacer (ITS) (or ITS2) have demonstrated reasonable levels of species discrimination in both floristic and taxonomically focused studies. We describe sampling techniques, extraction protocols, and PCR methods for each of these two core and two supplementary plant DNA barcode regions, with extensive notes supporting their implementation for both low- and high-throughput facilities.
Methods in molecular biology (Clifton, N.J.) 01/2012; 858:223-52.
[show abstract][hide abstract] ABSTRACT: • Premise of the study: Despite its small size, New Caledonia is characterized by a very diverse flora and striking environmental gradients, which make it an ideal setting to study species diversification. Thirteen of the 19 Araucaria species are endemic to the territory and form a monophyletic group, but patterns and processes that lead to such a high species richness are largely unexplored. • Methods: We used 142 polymorphic AFLP markers and performed analyses based on Bayesian clustering algorithms, genetic distances, and cladistics on 71 samples representing all New Caledonian Araucaria species. We examined correlations between the inferred evolutionary relationships and shared morphological, ecological, or geographic parameters among species, to investigate evolutionary processes that may have driven speciation. • Key results: We showed that genetic divergence among the present New Caledonian Araucaria species is low, suggesting recent diversification rather than pre-existence on Gondwana. We identified three genetic groups that included small-leaved, large-leaved, and coastal species, but detected no association with soil preference, ecological habitat, or rainfall. The observed patterns suggested that speciation events resulted from both differential adaptation and vicariance. Last, we hypothesize that speciation is ongoing and/or there are cryptic species in some genetically (sometimes also morphologically) divergent populations. • Conclusions: Further data are required to provide better resolution and understanding of the diversification of New Caledonian Araucaria species. Nevertheless, our study allowed insights into their evolutionary relationships and provides a framework for future investigations on the evolution of this emblematic group of plants in one of the world's biodiversity hotspots.
American Journal of Botany 12/2011; 99(1):68-81. · 2.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: DNA barcoding of a group of European liverwort species from the genus Herbertus was undertaken using three plastid (matK, rbcL and trnH-psbA) and one nuclear (ITS) marker. The DNA barcode data were effective in discriminating among the sampled species of Herbertus and contributed towards the detection of a previously overlooked European Herbertus species, described here as H. norenus sp. nov. This species shows clear-cut differences in DNA sequence for multiple barcode regions and is also morphologically distinct. The DNA barcode data were also useful in clarifying taxonomic relationships of the European species with some species from Asia and North America. In terms of the discriminatory power of the different barcode markers, ITS was the most informative region, followed closely by matK. All species were distinguishable by ITS alone, rbcL + matK and various other multimarker combinations.
[show abstract][hide abstract] ABSTRACT: Although often considered as evolutionary dead ends, selfing taxa may make an important contribution to plant evolution through hybridization with related outcrossing lineages. However, there is a shortage of studies examining the evolutionary dynamics of hybridization between outcrossing and selfing taxa. On the basis of differential pollinator attractiveness, production and competitive ability of pollen, as well as levels of inbreeding depression, we predict that the early products of hybridization between outcrossing and selfing lineages will be F1s and first-generation backcrosses sired mainly by the outcrossing lineage, together with selfed F2s containing a limited genetic contribution from the outcrosser. These predictions were tested using amplified fragment length polymorphism and chloroplast markers to analyze the composition of a recent hybrid swarm between predominantly outcrossing Geum rivale and predominantly selfing Geum urbanum. In line with predictions, the hybrid swarm comprised both parental species together with F1s and first-generation backcrosses to G. rivale alone. Chloroplast data suggested that G. rivale was the pollen parent for both observed hybrid classes. However, there was no evidence for F2 individuals, despite the fact that the F1 was fully self-compatible and able to auto-pollinate. The pollen fertility of F1s was only 30% lower than that of the parental taxa, and was fully restored in backcross hybrids. Predicting future evolution in the hybrid swarm will require an understanding of the mating patterns within and among the mix of parental, F1 and backcross genotypes that are currently present. However, these results support the hypothesis that introgression is likely to be asymmetrical from selfing to outcrossing lineages.
[show abstract][hide abstract] ABSTRACT: • Efforts are currently underway to establish a standard DNA barcode region for fungi; we tested the utility of the internal transcribed spacer (ITS) of nuclear ribosomal DNA for DNA barcoding in lichen-forming fungi by sampling diverse species across eight orders. • Amplification of the ITS region (ITS1-5.8S-ITS2) was conducted for 351 samples, encompassing 107, 55 and 28 species, genera and families, respectively, of lichenized fungi. We assessed the ability of the entire ITS vs the ITS2 alone to discriminate between species in a taxonomic dataset (members of the genus Usnea) and a floristic dataset. • In the floristic dataset, 96.3% of sequenced samples could be assigned to the correct species using ITS or ITS2; a barcode gap for ITS is present in 92.1% of species. Although fewer species have a barcode gap in the taxonomic dataset (73.3% with ITS and 68.8% with ITS2), up to 94.1% of samples were assigned to the correct species using BLAST. • While discrimination between the most closely related species will remain challenging, our results demonstrate the potential to identify a high percentage of specimens to the correct species, and the remainder to the correct genus, when using DNA barcoding in a floristic context.
New Phytologist 03/2011; 191(1):288-300. · 6.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: Fine-scale spatial genetic structure (FSGS) within plant populations is an emergent property of the recruited adult trees, influenced by pollen and seed mediated gene flow, selection and demographic processes. This study aims to increase our understanding of the individual species traits that contribute to the generation of FSGS in the Dipteropcarpaceae, which is an ecologically and economically important family of tropical trees that dominate lowland forests in Southeast Asia. We examined FSGS in three co-occurring dipterocarp species at a single site in Borneo. Shorea xanthophylla, Parashorea tomentella and Dipterocarpus grandiflorus share limited seed dispersal but differ markedly in flower size, pollinator body size and pollen dispersal. Here we explore the role of pollen dispersal limitation in shaping FSGS in these three species. Using six microsatellite loci, we explore patterns of FSGS and landscape genetic structure and compare these across species. Significant FSGS was observed in S. xanthophylla and P. tomentella, both of which are known to have relatively limited pollen dispersal, but no clear signal of FSGS was observed in D. grandiflorus. Significantly greater FSGS was observed in P. tomentella (Sp = 0.012) than S. xanthophylla (Sp = 0.007) despite greater pollen dispersal in P. tomentella. Bayesian clustering analysis revealed significant structure in P. tomentella at the scale of the forest reserve (4000 ha). We discuss the alternative explanations for the observed patterns of FSGS emphasising the complexity of the mechanisms that can generate FSGS in long-lived trees. The extent of species-specific pollen dispersal is one factor that can contribute to differences in FSGS across species, but is not the only determinant. The observed patterns of FSGS and landscape scale genetic structure in S. xanthophylla and P. tomentella illustrate the potential of gap regeneration to counter act pollen dispersal and contribute to increased aggregation of related individuals (FSGS).
Perspectives in Plant Ecology, Evolution and Systematics. 01/2011;
[show abstract][hide abstract] ABSTRACT: The main aim of DNA barcoding is to establish a shared community resource of DNA sequences that can be used for organismal identification and taxonomic clarification. This approach was successfully pioneered in animals using a portion of the cytochrome oxidase 1 (CO1) mitochondrial gene. In plants, establishing a standardized DNA barcoding system has been more challenging. In this paper, we review the process of selecting and refining a plant barcode; evaluate the factors which influence the discriminatory power of the approach; describe some early applications of plant barcoding and summarise major emerging projects; and outline tool development that will be necessary for plant DNA barcoding to advance.
PLoS ONE 01/2011; 6(5):e19254. · 3.73 Impact Factor